In large machines of this type, in particular for electricity production in a power station, the stator has a stator winding which is formed by a plurality of winding bars. These winding bars, which are generally in the form of so-called Roebel bars, in this case extend in the axial direction in a stator core. The ends of the winding bars are passed out of the stator core at least on one axial end face of this stator core. The winding bar ends which are passed out are normally bent in the radial direction and in the circumferential direction, and are arranged such that they form a frustoconical or funnel-shaped end winding on the core end face, the diameter of which end winding increases as the distance from the core end face increases.
The stator winding of the electrical machine is provided with a plurality of connecting terminals, in order to allow electrical power to be fed into the stator winding and/or to be fed out of the stator winding, depending on whether the electrical machine is designed and/or is being operated as an electric motor or as a generator. For this purpose, selected winding bars, so-called phase winding bars, must be connected to these connecting terminals.
By way of example, this can be done in the end winding by phase connector bars, so-called round connectors, which each connect one of the phase winding bars in the area of the core end face to one of the connecting terminals.
In general, the phase connector bars extend between their ends in the form of an annular segment in the circumferential direction of the stator, in which case they are supported radially internally on one or more supports, normally in the form of supporting brackets, which are arranged distributed in the circumferential direction in the area of the core end face. The round connectors are arranged on the outer face of these supporting brackets and are frequently attached to the supporting brackets. In general, a plurality of round connectors are located axially (with respect to the stator axis) one behind the other between axial stops on the supporting brackets. Spacers are expediently arranged in each case between adjacent round connectors in the area of the supports, on which spacers the round connectors come to rest axially. The sizes of the spacers are in this case expediently adapted such that they result in an interference fit, after being fitted in the axial direction, for the round connectors which are arranged between the axial stops. This results in the round connectors being effectively fixed on the supporting brackets, as is necessary because of the loads which occur during operation of the electrical machine.
The round connectors are normally provided with insulation, in general a synthetic resin, on their outer face. During curing of the resin and because of the heating and vibrations which occur during operation of the electrical machines, seating phenomena can occur, in the course of which the insulation on the round connectors can flex slightly in the axial direction. This results in a major decrease in the axial pressure in the interference fit between the axial stops on the supports, which can lead to the axial holding forces being reduced during continuous operation of the respective machine. Designs and improvements such as these relating to the configuration of the spacers and the retention of the round connectors are disclosed, for example, in DE 102004016454.
WO 2008/138704 discloses that it is possible to attach the round connectors to the supporting brackets by knurling and an entire supporting basket, formed from supporting brackets which are distributed over the circumference and are connected by an outer and an inner supporting ring, and the round connectors which are arranged on the outer face of the supporting brackets and are attached thereto being introduced in their entirety into an impregnation agent bath.